Clinching offers a breath of fresh air in H&V applications
On the face of it the process of clinching would appear to be a straightforward process: that of squeezing two or more sheets of metal together in a way that joins them together permanently. However, as with most allegedly ‘simple’ things, there are an infinite number of variables that can come into play
On an engineering application where the joining of sheet metals is required, any two of these variables can combine to present challenges to design teams. But it is often the case that more than two variables need to be considered concurrently, and this is where things can begin to get complicated from a joining viewpoint.
For example, in some materials joining applications, structural strength might be a primary consideration, or perhaps resistance to a bending moment. In others, if the joined sections or parts are in full view then the visual ‘look’ of the joints themselves might lead the design team to seek a joining process or method that also provides a visually appealing solution.
Occasionally however, there are applications where joint integrity needs to encompass rather more than simply keeping various metal parts together, resisting bending moments and/or looking good. An example of this is illustrated in the H&V market, where a primary consideration for the design team might be the integrity of ducting joints in respect of their ability to prevent the leakage of gases, exhausts or contaminated air from inside the ducting.
Given the scale of some ducting installations and the substantial amount of material used in them, the potential cost implications of removing and reinstalling any joints which leak can be significant.
But the threat to the health and wellbeing of any persons nearby is a completely different matter in the event of leakage occurring. So in many applications in the H&V market it is becoming more common to see Bollhoff Fastenings’ Rivclinch process used for joining ducting sections. The company states that its process is the only one of its type to have secured TUV Type D air tightness certification covering “Duct connections for sheet metal air ducts with rectangular sections.” The TUV Certification provides designers, installers and users with an independent assurance that the joints have passed stringent assessments and thus deliver an assurance against the leakage of gases.
Capable of joining up to three layers of sheet metal with a combined thickness of up to 3.5mm, the Rivclinch system is also a joining method that doesn’t involve the drilling or punching of any holes in the material, rendering it ideal for use with pre-coated or pre-painted sheet. Typical joining cycle times vary between 0.5/sec and 0.9sec dependent upon material thickness so the process is swift too.
The Rivclinch tooling has been configured for use by companies large and small and to this end can be specified in a wide range of configurations from hand-held tools weighing less than 6kg in gyroscopic suspension for low volume work right up to fully automated PLC controlled bespoke systems with multiple joining heads for high-throughput, heavier duty projects.
Capable of fastening mild steel, stainless steel, aluminium and non-ferrous metals using the same tooling, the Rivclinch cold joining technique allows manufacturers to embrace other advantages that may be not be immediately obvious at first glance. For example, it allows OEMs to dispense with the need for loose fasteners and helps prevent the onset of corrosion in the joined parts because the material is deformed not pierced. Moreover, where required, the Rivclinch process also permits the use of other laminates or bonding/sealing agents to be introduced as layers between the joined sheets or panels as well.
An additional feature offered by Rivclinch is a choice of the shape of the joint itself. Users can specify either a round or rectangular version of the joint at the point of contact. Further advantages include the reduction of energy used compared to welding and a fume-free environment for production staff engaged on the assembly and joining processes.
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